Respect SYSTEM_EXT_ROOT in odrefresh am: 0a964610eb am: 79ba38e312 am: 9781b7bf27 am: 9be0758a4c

Original change: https://android-review.googlesource.com/c/platform/art/+/2225897

Change-Id: I019c626653fdc65c7835c73a9f1f77bf40a6d4a9
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>